Water Cooled

8/6/2019 Water Cooled

1/14

Chillers

28PA RT28

H VA C E Q U ATI O N S , D ATA , A N D R U L E S O F T H U M B


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488 PART 28

28.01 Chiller Types and Manufacturer Offerings

Chiller Type CapacityRange tonskW/ton

Range (1)COP

Range (1)Turndown %

Capacity Refrigerant Comments

CentrifugalWater Cooled

Carrier 2001500 0.550.62 5.666.39 10 134a 3

McQuay

1251250 0.500.60 5.857.02 10 134a 3

2502400 0.500.60 5.857.02 10 134a 4

12002700 0.500.60 5.857.02 10 134a 5

Trane2002000 0.450.55 6.397.80 10 123 3

15004000 0.450.55 6.397.80 10 123 4

York 2002400 0.500.60 5.857.02 10 134a 3

20006000 0.500.60 5.857.02 10 134a 4

CentrifugalWater Cooled with Unit Mounted VFD

Carrier 200800 0.550.62 5.666.39 10 134a 3

McQuay1251250 0.500.60 5.857.02 10 134a 3

2502400 0.500.60 5.857.02 10 134a 4

Trane 2001500 0.450.55 6.397.80 10 123 3

York 2001475 0.500.60 5.857.02 10 134a 3

ReciprocatingAir Cooled

Carrier NA NA NA NA NA

McQuay NA NA NA NA NA

Trane NA NA NA NA NA

York NA NA NA NA NA

ReciprocatingWater Cooled

Carrier 1560 0.810.99 3.594.32 2050 22

McQuay NA NA NA NA NA

Trane NA NA NA NA NA

York NA NA NA NA NA

Rotary ScrewAir Cooled

Carrier 75455 1.131.25 2.803.10 615 134a

McQuay 110500 1.151.25 2.803.05 15 134a

Trane140500 1.051.16 3.033.34 15 134a

70125 1.051.13 3.113.34 20 22 2

York 150500 1.151.20 2.933.05 15 134aRotary ScrewWater Cooled

Carrier300500 0.550.62 5.666.39 10 134a 6

75265 0.690.72 4.885.09 1320 134a

McQuay 120190 0.540.70 4.936.50 15 134a

Trane140450 0.580.70 5.026.05 15 134a

70125 0.740.76 4.624.75 20 22 2

York 90400 0.600.75 4.685.85 15 22, 407c, 134a

ScrollAir Cooled

Carrier60390 0.840.91 3.874.16 1020 410c

1055 1.191.25 2.802.96 1530 22McQuay 10130 1.201.25 2.802.93 1530 22, 407c

Trane 1060 1.051.20 2.933.34 25, 50 22 2

York 15130 1.001.15 3.053.51 20 22, 407c

ScrollWater Cooled

Carrier NA NA NA NA NA

McQuay 30120 0.770.78 4.504.55 25 22

Trane 2060 0.770.78 4.504.56 25, 50 22 2

York NA NA NA NA NA


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Notes:

1 KW/ton and COPs are based on full load operating characteristics and are ball park figures. KW/ton andCOPs above and below the values listed in the table are possible for all manufacturers depending on desiredoperating characteristics. KW/ton,COP, and capacities are driven by, and will vary from, the values listed in thetable based on chilled water supply/return temperatures, condenser water supply/return temperatures (water-cooled machines),outside air temperatures (air-cooled machines), and type of refrigerant.

2 The Refrigerant HCFC-22 product will be changing to 134a by the end of 2007.3 Centrifugal chillers with single compressor.4 Centrifugal chillers with dual compressors.5 Centrifugal chillers with dual compressors and dual refrigerant circuits.6 Variable speed drive screw chiller.7 COP, EER, and kW/ton relationships:

EER = COP 3.417COP = 12,000 / (kW/ton 3,417)kW/ton = 12,000 / (COP 3,417)

28.02 Chiller Motor Types

A. Hermetic Chillers/Motors

1. Motors are refrigerant cooled.2. Motor heat absorbed by the refrigerant must be removed by the condenser cooling

medium (air or water).3. TONSCOND TONSEVAP 1.25

12,000 Btu/hr. ton 1.25 15,000 Btu/hr. ton.Therefore, motor heat gain is approximately 3,000 Btu/hr. ton.

B. Open Chillers/Motors

1. Motors are air cooled.2. Motor heat is rejected directly to the space. Therefore, the space HVAC system must

remove approximately 3,000 Btu/hr. ton of motor heat gain.

C. In either case, the chillers must remove the 3,000 Btu/hr. ton of heat generated bythe motors; the only difference is the method by which it is accomplished.

28.03 Code Required Chiller Efficiencies

Equipment Type Equipment CapacitySize Range

2003 IECC

2006 IECC

ASHRAE Std. 90.1-2001

ASHRAE Std. 90.1-2004COP kW/TON COP kW/TON

Air-Cooled Chillers withCondenserElectric

< 150 tons 2.80 1.254 2.80 1.254150 tons 2.50 1.405 2.80 1.254

Air-Cooled Chillers withoutCondenserElectric All Capacities 3.10 1.133 3.10 1.133

Water-Cooled ReciprocatingChillersElectric All Capacities 4.20 0.836 4.20 0.836

Water-Cooled Rotary Screwand Scroll ChillersElectric

< 150 tons 4.45 0.789 4.45 0.789150 tons and < 300 tons 4.90 0.717 4.90 0.717300 tons 5.50 0.639 5.50 0.639

Water-Cooled CentrifugalChillersElectric

< 150 tons 5.00 0.702 5.00 0.702150 tons and < 300 tons 5.55 0.633 5.55 0.633300 tons 6.10 0.576 6.10 0.576

Air-Cooled AbsorptionChillersSingle Effect All Capacities 0.60 5.853 0.60 5.853

Water Cooled AbsorptionChillersSingle Effect All Capacities 0.70 5.017 0.70 5.017

Absorption ChillersDouble Effect, Indirect Fired All Capacities 1.00 3.512 1.00 3.512

Absorption ChillersDouble Effect, Direct Fired All Capacities 1.00 3.512 1.00 3.512


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Notes:

1 Efficiency values apply to chillers with water temperatures above 40 F.2 1 ton 3,417 kW.3 For centrifugal chillers operating at temperatures other than 44 F chilled water, 85 F condenser water, and 3.0

GPM/ton condenser water flow rate, see the following table.

CENTRIFUGAL CHILLERS2003 IECC and 2006 IECC

ASHRAE Std. 90.1- 2001 and ASHRAE Std. 90.1 - 2004

LeavingChilledWater

Temp. F

EnteringCondenser

WaterTemp. F

Less than 150 tons 150 tons to 300 tons Greater than 300 tons

2 GPM/ton15F T

3 GPM/ton10F T

2 GPM/ton15F T

3 GPM/ton10F T

2 GPM/ton15F T

3 GPM/ton10F T

COP kW/ton COP kW/ton COP kW/ton COP kW/ton COP kW/ton COP kW/ton

48 85 4.94 0.691 5 .32 0.641 5.46 0.625 5.89 0.579 6.02 0.567 6.49 0.526

47 85 4.84 0.705 5 .25 0.650 5.35 0.638 5.80 0.588 5.90 0.578 6.40 0.533

46 85 5.094.73

0.6700.721

5.565.17

0.6140.660

5.23 0.652 5.71 0.598 5.77 0.591 6.30 0.542

45 854.964.62

0.6880.739

5.475.09

0.6240.670

5.10 0.669 5.62 0.607 5.63 0.606 6.20 0.550

44 854.834.49

0.7060.760

5.405.00

0.6320.682

4.96 0.688 5.55 0.615 5.47 0.624 6.10 0.559

43 854.684.35

0.7290.784

5.284.91

0.6460.695

4.81 0.709 5.42 0.630 5.30 0.643 5.98 0.571

42 854.514.19

0.7570.814

5.174.81

0.6600.709

4.63 0.737 5.31 0.643 5.11 0.668 5.86 0.582

41 854.33

4.02

0.788

0.849

5.05

4.70

0.676

0.726

4.45 0.767 5.19 0.657 4.90 0.696 5.72 0.597

40 854.133.84

0.8260.889

4.924.58

0.6930.745

4.24 0.805 5.06 0.674 4.68 0.729 5.58 0.611

Notes:

1 Where two values are provided,the top number is for the 2003 IECC and 2006 IECC, the bottom is for ASHRAEStd. 90.1-2001 and ASHRAE Std. 90.1-2004.

2 Chilled-water temperatures are only provided in ASHRAE Std. 90.1-2001 and ASHRAE Std. 90.1-2004.3 The number in bold are standard rating conditions listed in the previous table.4 For conditions other than those listed in the preceding table, see 2003 IECC, 2006 IECC, ASHRAE Std. 90.1-

2001, ASHRAE Std. 90.1-2004, or use the following equations.

Lift Entering Condenser Water Temperature ( F) Leaving Chilled Water Temperature ( F).Condenser T Leaving CondenserWater Temperature ( F) Entering CondenserWater Temperature ( F).

X Condenser T Lift.Kajd 6.1507 0.30244(X) 0.0062692(x)2 0.000045595(x) 3.COPadj Kadj COPstd

28.04 Chiller Terms

A. Refrigeration Effect . The refrigeration effect is the amount of heat absorbed bythe refrigerant in the evaporator.

B. Heat of Rejection . The heat of rejection is the amount of heat rejected by therefrigerant in the condenser, which includes compressor heat.

C. Subcooling . Subcooling is the cooling of the refrigerant below the temperature atwhich it condenses. Subcooling the liquid refrigerant will increase the refrigera-tion effect of the system.

D. Superheating . Superheating is the heating of the refrigerant above the tempera-ture at which it evaporates. Superheating the refrigerant by the evaporator is partof the system design to prevent a slug of liquid refrigerant from entering the com-pressor and causing damage.


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E. Coefficient of Performance (COP) . The coefficient of performance is defined asthe refrigeration effect (Btu/hr.) divided by the work of the compressor (Btu/hr.).

Another way to define COP is Btu output divided by Btu input. COP is equal toEER divided by 3.413.

F. Energy Efficiency Ratio (EER) . The energy efficiency ratio is defined as therefrigeration effect (Btu/hr.) divided by the work of the compressor (watts).

Another way to define EER is the Btu output divided by the watts input. The EERis equal to 3.413 times the COP.

G. pH Chart . Pressure/Enthalpy chart is a graphic representation of the propertiesof a specific refrigerant with the pressure on the vertical axis and the enthalpy onthe horizontal axis. The graph is used and is helpful in visualizing the changesthat occur in a refrigeration cycle.

H. Integrated Part Load Value (IPLV) ARI Specified Conditions . Acceptabletolerances for specified conditions are 65 percent.

I. Application Part Load Value (APLV) Engineer Specified Conditions (Real World Conditions) . Acceptable tolerances for specified conditions are 6.5 percent.

J. Rupture Disc . A relief device on low-pressure machines.

K. Relief Valve . A relief device on high-pressure machines.

L. Pumpdown . Refrigerant pumped to the condenser for storage.

M. Pumpout . Refrigerant pumped to a separate storage vessel. Use pumpout type storage when a reasonable size and number of portable storage containers can-not be moved into the building.

N. Purge Unit . Removes air from the refrigeration machine; required on low-pressure machines only.

O. Prevac . Device that prevents air from entering the refrigeration machine. It is usedto leak test the refrigeration machine. Required on low-pressure machines only.

P. Factory Run Tests . 1,500 tons and smaller; most manufacturers can provide them.

1. Certified Test . Certifies performancefull load and/or part loadIPLV, and/or APLV.2. Witnessed Tests:a. Generic . Any chiller the manufacturer produces of the same size and characteristics.b. Specific . The specific chiller required by the customer.

Q. Hot Gas Bypass . Low limit to suction pressure of the compressor. Hot gas bypassis beneficial on DX systems and generally not beneficial on chilled-water systems,except when tight temperature tolerances are required for a manufacturing pro-cess. Chillers specified with both hot gas bypass and low ambient temperaturecontrol will result in the hot gas bypass increasing the low ambient temperatureoperating point of the chiller (decreases the ability for the chiller to operate at low

ambient conditions).

28.05 Basic Refrigeration Cycle Terminology

A. Compressor . Mechanical device where the refrigerant is compressed froma lower pressure and lower temperature to a higher pressure and highertemperature.


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B. Hot Gas Piping . Refrigerant piping from the compressor discharge to the com-pressor suction, to the evaporator outlet, or to the evaporator inlet, or from thecompressor discharge and the condenser outlet to the compressor suction.

C. Condenser . Heat exchanger where the system heat is rejected and the refrigerantcondenses into a liquid.

D. Liquid Piping . Refrigerant piping from the condenser outlet to the evaporator inlet.

E. Evaporator . Heat exchanger where the system heat is absorbed and the refriger-ant evaporates into a gas.

F. Suction Piping . Refrigerant piping from the evaporator outlet to the compressor suction inlet.

G. Thermal Expansion Valve . Pressure and temperature regulation valve, locatedin the liquid line, which is responsive to the superheat of the vapor leaving theevaporator coil.

28.06 Chiller Energy Saving Techniques

A. Constant Speed Chillers . For each 1 F increase in chilled-water temperature, thechiller efficiency increases 1.02.0 percent.

B. Variable Speed Chillers . For each 1 F increase in chilled-water temperature, thechiller efficiency increases 2.04.0 percent.

C. For each 1 F decrease in condenser water temperature, the chiller efficiencyincreases 1.02.0 percent.

28.07 Cooler (Evaporator) / Chilled-Water System

A. Leaving Water Temperature (LWT): 4246 F

B. 1020 F T

C. 2.4 GPM/ton@10 F T

D. 2.0 GPM/ton@12 F T

E. 1.5 GPM/ton@16 F T

F. 1.2 GPM/ton@20 F T

G. 5,000 Btuh/GPM@10 F T

H. 6,000 Btuh/GPM@12 F T

I. 8,000 Btuh/GPM@16 F T

J. 10,000 Btuh/GPM@20 F T

K. ARI Evaporator Fouling Factor: 0.00010 Btu/hr.ft. 2 F

L. Chilled Water Flow Range: Chiller Design Flow 10 percent

M. Chiller Tube Velocity for Variable Flow Chilled Water

1. Minimum flow: 3.0 FPS.2. Maximum flow: 12.0 FPS.


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28.08 Condenser / Condenser Water Systems

A. Entering Water Temperature (EWT): 85 F

B. T Range: 1020 F

C. Normal T: 10 F

D. 3.0 GPM/ton@10 F T

E. 2.5 GPM/ton@12 F T

F. 2.0 GPM/ton@15 F T

G. 1.5 GPM/ton@20 F T

H. 5,000 Btuh/GPM@10 F T

I. 6,000 Btuh/GPM@12 F T

J. 7,500 Btuh/GPM@15 F T

K. 10,000 Btuh/GPM@20 F T

L. ARI Condenser Fouling Factor: 0.00025 Btu/hr. ft. 2 F

28.09 Chilled Water Storage Systems

A. 10 F T

1. 19.3 cu.ft./ton hr.2. 623.1 Btu/cu.ft.; 83.3 Btu/gal.

B. 12 F T


C. 16 F T


D. 20 F T


28.10 Ice Storage Systems

A. 144 Btu/lb.@32 F 0.48 Btu/lb. for each 1 F below 32 F.

B. 3.2 cu.ft./ton hr.

C. Only the latent heat capacity of ice should be used when designing ice storage systems.


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28.11 Water-Cooled Condensers

A. Entering Water Temperature (EWT): 85 F

B. Leaving Water Temperature (LWT): 95 F

C. 3.0 GPM/ton@10 F T

D. For each 1 F decrease in condenser water temperature, chiller efficiencyincreases 11.2 percent.

28.12 Refrigerant EstimateSplit Systems

A. Total 3.0 lbs./ton

B. Equipment 2.0 lbs./ton

C. Piping 1.0 lbs./ton

28.13 Chilled Water System Makeup Connection

Minimum connection size shall be 10 percent of the largest system pipe size or 1",whichever is greater. (A 20" system pipe size results in a 2" makeup water connection.)

28.14 Chemical Feed Systems for Chillers. Chemical FeedSystems are Designed to Control the Following

A. System pH, normally between 8 and 9.

B. Corrosion.

C. Scale.

28.15 Chiller Operating Sequence

A. Start chilled water and condenser water pumps. Verify chilled water and con-denser water flow.

B. Start chiller and cooling tower.

C. Runtime.

D. Stop chiller and cooling tower.

E. Stop chilled water and condenser water pumps after 0- to 30-second delaybecause some chiller manufacturers use chilled water or condenser water to coolthe solid state starter circuitry.

F. Chiller Startup Piping (see Fig. 28.1)

1. Because it takes 515 minutes from the time the chiller start sequence is initiated untilthe time the chiller starts to provide chilled water at the design temperature, the chilledwater supplytemperatureoften rises above thedesired control setpoint.If thechilled watersupply temperature is critical, the method to correct this problem is to provide the chillerswith startup piping which runs from the chiller discharge to the pump return main.


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FIGURE 28.1 CHILLER STARTUP PIPING DIAGRAM.


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2. The designer should size startup piping for the flow of the largest chiller in the system.The common pipe size only needs to be sized for the flow of one chiller because it isunlikely that more than one chiller will be started at the same time.

3. Chilled water system operation with startup piping should be as follows:a. On initiation of the chiller start sequence, the primary chilled water pump is started,

the bypass valve is opened, and the supply header valve is closed. When the chilledwater supply setpoint temperature is reached, as sensed in the bypass, the supply header valve is slowly opened, maintaining the setpoint temperature at all times.When the supply header valve is fully opened, the bypass valve is slowly closed.

b. On initiation of the chiller stop sequence, the bypass valve is slowly opened. Whenthe bypass valve is fully opened, the supply header valve is slowly closed. The chilleris stopped, and after a delay, the primary chilled water pump is stopped. When theprimary chilled water pump stops, the bypass valve is left open to permit water toexpand into, or contract from, the system. On headered systems, the chilled waterreturn valve must be closed as well.

4. The chilled water diagram shows the chiller startup piping with motorized shutoff valves. Motorized valves are required for automatic or remote manual control. If thechilled water system will be manually operated, these valves may be deleted. A separatemanual shutoff valve has also been provided to allow for manual isolation of the systemand to permit repair of the motorized valve without having to shut down the system.This manual shutoff valve may be deleted, provided the motorized shutoff valve has amanual means by which it can be opened and closed. Most motorized control valves donot have a manual means to open and close them.

28.16 Chiller Design, Layout, and ClearanceRequirements/Considerations

A. Design Conditions

1. Chiller load. Tons, Btu/hr., or MBH.2. Chilled water temperatures. Entering and leaving or entering and T.3. Condenser water temperatures. Entering and leaving or entering and T.4. Chilled water flows and fluid type (correct all data for fluid type).5. Condenser water flows and fluid type (correct all data for fluid type).6. Evaporator and condenser pressure drops.7. Fouling factor.8. IPLV, desirable.9. APLV, optional.

10. Chilled water or condenser water reset if applicable.11. Ambient operating temperature, dry bulb and wet bulb.12. Electrical data:

a. Compressor or unit KW.b. Full load, running load, and locked rotor amps.c. Power factor.

d. Energy Efficiency Ratio (EER).e. Voltage-phase-hertz.

B. Multiple chillers should be used to prevent complete system or building shutdownupon failure of one chiller in all chilled water systems over 200 tons (i.e., 2@50percent, 2@67 percent, 2@70 percent, 3@34 percent, 3@40 percent).

1. Series chiller design: Piping chillers in series can accomplish large temperature differen-tials without penalizing the chiller performance (see Fig. 28.2 and Fig. 28.3).

2. Parallel chiller design: Piping chillers in parallel provides a simpler installation and pro-vides formultiple chiller arrangementswithstandby opportunities.Standby opportunities


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are also available with series chiller arrangements, but they become more complex andcumbersome (see Fig. 28.4 and Fig. 28.5).

3. When designing chilled water systems for computer centers, data centers, Internet hostsites, and other mission-critical facilities where down time is not acceptable, considerutilizing a dual primary/secondary chilled-water system with primary/secondary chilled-water cross-connections and looped secondary system (see Fig. 28.6 and Fig. 28.7). Thischilled-water system design permits isolating the piping segments as well as the equip-ment to permit service and repairs to both piping and equipment without shutdown of the system. The dual primary/secondary chilled-water system can be designed and sizedto meet the Uptime Institutes Tier III classification (N 1 redundancy requirements; thearrangement actually provides N 2) and Tier IV classification (2[N 1] redundancy requirements). Chilled-water systems serving mission-critical facilities should always bedesigned for future expansion and growth. All future equipment and systems must pro-vide for this growth. Space must be provided for future equipment, valved and cappedconnections must be provided for connections to piping mains so shutdowns are notrequired,piping mains must be sized for the ultimate growth of the facility, and electricalpower systems must be designed and sized for the ultimate power utilized by the facility.

C. Water Boxes/Piping Connections

1. Marine type. Marine water boxes enable piping to be connected to the side of the chillerso piping does not need to be disconnected in order to service machine. Recommend onlarge chillers, 500 tons and larger.

2. Nonmarine or standard type. Recommend on small chillers, less than 500 tons.3. Provide victaulic or flanged connections for first three fittings at chiller with nonmarine

or standard type connections.

FIGURE 28.2 SERIES CHILLED WATER SYSTEM.

FIGURE 28.3 SERIES CHILLED WATER SYSTEM WITH LEAD-LAG CHILLER CONTROL.


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4. Locate piping connections against the wall.5. Locate all piping connections opposite the tube clean/pull side of the chiller.6. Locate oil cooler connections.

D. Show tube clean/pull clearances and location.

E. The minimum recommended clearance around chillers is 36 inches. Maintainminimum clearances for tube pull and cleaning of tubes as recommended by theequipment manufacturer. This is generally equal to the length of the chiller. Main-

tain minimum clearance as required to open access and control doors on chillersfor service, maintenance, and inspection.

F. Maintain minimum electrical clearances as required by NEC.

G. Mechanical room locations and placement must take into account how chillerscan be moved into and out of the building during initial installation and after con-

struction for maintenance and repair and/or replacement.

H. If the chiller must be disassembled for installation (the chiller cannot be shippeddisassembled), specify the manufacturers representative for reassembly; do not

specify insulation with chiller (field insulate), and specify the chiller to come withremote mounted starter.

FIGURE 28.4 PARALLEL CHILLED WATER SYSTEMCOUPLED PUMPS.

FIGURE 28.5 PARALLEL CHILLED WATER SYSTEMHEADERED PUMPS.


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I. Show the location of the chiller starter. Disconnect the switch and the control panel.

J. Show the chiller relief piping.

K. Show sanitary drain locations and chiller drain connections.

L. Locate refrigerant monitoring system refrigerant sensors, and the refrigerantpurge exhaust fan. The refrigerant exhaust system should be designed to removerefrigerant based on its specific gravity (lighter than airhigh exhaust, heavierthan airlow exhaust). Refrigerant detection devices are required by code,

FIGURE 28.6 DUAL PRIMARY/SECONDARY CHILLED WATER SYSTEM FLOW DIAGRAM.

FIGURE 28.7 LOOPED SECONDARY CHILLED WATER SYSTEM FLOW DIAGRAM.


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ASHRAE Standard 15. Detection devices sound an alarm at certain levels (lowlimit) and sound an alarm and activate ventilation system at a higher level (highlimit), with levels dependent on refrigerant type.

M. Providing self-contained breathing apparatus within buildings for refrigerantemergencies is not recommended as in previous versions of ASHRAE Standard 15.Pre-positioning emergency response equipment should only be used by trainedemergency responders and must be labeled for use by trained personnel only.

N. Coordinate the height of the chiller with overhead clearances and obstructions. Isa beam required above the chiller for lifting the compressor or other components?

O. Low ambient operation. Is the operation of the chiller required below 40 F, 0 F,etc., or will airside economizers provide cooling?

P. Wind direction and speed (air-cooled machines). Orient the short end of thechiller to the wind.

Q. If isolators are required for the chiller, has the isolator height been considered inclearance requirements? If isolators are required for the chiller, has piping isola-tion been addressed?

R. Locate flow switches in both the evaporator and condenser water piping systems serving each chiller and flow meters as required by system design.

S. Locate pumpdown, pumpout, and refrigerant storage devices if they are required.

T. When combining independent chilled-water systems into a central plant1. Create a central system concept, control scheme, and flow schematics.2. The system shall only have a single expansion tank connection point sized to handle

entire system expansion and contraction.3. All systems must be altered, if necessary, to be compatible with central system concept

(temperatures, pressures, flow conceptsvariable or constant control concepts).4. For constant flow and variable flow systems, the secondary chillers are tied into the main

chiller plant return main. Chilled water is pumped from the return main through thechiller and back to the return main.

5. District chilled water systems, due to their size, extensiveness, or both, may require thatindependentplantsfeed into thesupplymain at different points. If this is required,designand layout must enable isolating the plant; provide start-up and shutdownbypasses; andprovide adequate flow, temperature,pressure, and other control parameter readings andindicators for proper plant operation and other design issues that affect plant operationand optimization.

U. In large systems, it may be beneficial to install a steam-to-water or water-to-water heat exchanger to place an artificial load on the chilled-water system totest individual chillers or groups of chillers during plant startup, after repairs, orfor troubleshooting chiller or system problems.

V. Large and campus chilled-water systems should be designed for large delta Tsand for variable flow secondary and tertiary systems.

W. Chilled-water pump energy must be accounted for in the chiller capacity becauseit adds heat load to the system.

X. It is best to design chilled-water and condenser-water systems to pump throughthe chiller.

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